Glossary E

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E: Voltage (electromotive force)
E-Mail: See Electronic Mail
E1: The European equivalent to the North American T1 carrier trunk. E1 users a 2.048 Mbps transmission rate.
Earth: British terminology for zero-reference ground
EBCDIC: See Extended Binary Coded Decimal Interchange Code
Echo: The name given to the ICMP packets used to check the reachability of nodes or devices on a network system. These packets are sometimes referred to a "Ping" packets.
EEHLLAPI: See Entry Emulator High Level Language Applications Interface
EFF: See Electronic Frontier Foundation
EGP: See Exterior Gateway Protocol
EIA: See Electronics Industry Association
EIA RS-455: The EIA “Standard Fiber Optic Test Procedures for Optical Fibers, Cables, Transducers, Connecting & Termination Devices”, RS-455 includes Fiber Optic Test Procedures (FOTP) for many of the mechanical & optical requirements of optical fiber cables.
EIA/TIA-568: EIA/TIA-568A The latest version of the “Commercial Building Telecommunications Wiring Standard” which has become one of the dictating standards for copper & fiber performance.
EISA: See Extended Industry Standard Architecture
Elastomer: Any material that will return to its original dimensions after being stretched or distorted.
Electrical Closet: A floor-serving facility for housing electrical equipment, panel boards & controls. The closet is the recognized interface between the electrical backbone riser & its associated pathway.
Electrical Ground: One of four functions categories of DTE-DCE interface signals. These signals provide common electrical points & discharge static & harmful voltages.
Electromagnetic: Referring to the combined electric & magnetic fields caused by electron motion through conductors.
Electromagnetic Interference: (EMI) Refers to the electrical & magnetic signals generated & transmitted by electronic & electrical equipment. Electromagnetic signals from some sources are strong enough to interfere with the proper operation of electronic equipment such as net working devices.
Electron Volt: A measure of the energy gained by an electron falling through an electric field produced by one volt.
Electronic Frontier Foundation: (EFF) A foundation that addresses social & legal issues arising from the impact of computers on society.
Electronic Mail: (E-Mail) An application with which users can send information to other users with whom they share a data communication connection.
Electronics Industry Association: (EIA) An organization responsible for establishing communication signal characteristics.
Electrostatic: Pertaining to static electricity, or electricity at rest. An electric charge, for example.
EMF: Electromotive force (voltage).
EMI: See Electromagnetic Interference
EMI/RFI: See Radio Frequency Interference
Emulation: The imitation of all or part of one device, terminal, or computer by another, so that the imitating device accepts the same data, performs the same functions, & appears to other network devices as if it were the imitated devices.
Encapsulate: A basic protocol layering technique. The information from a higher level protocol (which may include both data & headers) is carried as the data portion of lower-level protocol, which adds its own header information. For example, IP datagrams are encapsulated in Data Link packets.
Encoding/Decoding: Organizing information into a format suitable for transmission, & then reconverting it after transmission; for pulse-code modulated voice transmission, the generation of digital signal to represent quantized samples, & the subsequent reverse process.
Encryption: The basis of network security. Encryption encodes network packets to prevent anyone except the intended recipient from accessing the data.
End of Text: EXT
End of Transmission: (EOT) A control character in Data Link Control (DLC). EOT is sent by a DTE to indicate conclusion of transmission.
End of Transmission Block: (ETB) A control character in the DLC, ETB indicates the end of an "Immediate" block.
End-to-end: An expression used in the networking environment to indicate communication between source & destination nodes on a network system. End-to-end communication is carried out by the transport layer of TCP/IP.
Enhanced Small Device Interface: (ESDI) an Interface type for computer adapter & controller boards.
Enterprisewide Network: A Internetwork connecting all sites of a single corporation worldwide.
Entry Emulator High Level Language Applications Interface: (EEHLLAPI) An IBM API subset of HLLAPI.
EOT: See End of Transmission
EPROM: See Erasable Programmable Read-Only Memory
Equipment Room: A room that serves the space needs for larger telecommunications equipment. Note: These are often special purpose rooms. Equipment rooms are connected to the backbone facility.
Erasable Programmable Read-Only Memory: (EPROM) A nonvolatile semiconductor PROM that can be erased by exposing it to intense ultraviolet light for reuse.
Erasable Storage: A storage device whose contents can be modified, (e.g. Random Access Memory, or RAM), as contrasted with read-only storage (e.g. Read-Only Memory, or ROM).
Error: A term used to describe signals with a rate or value below the accepted norms. An error may be caused by mutilation of bits, loss of bits or character, or improper DLC (Data Link Control) procedure.
Error Condition: The discrepancy between the sent data & the received data. Error condition may be caused by mutilation of bits, loss of bits or characters, or improper use of DLC procedure.
Error Rate: A measure of data integrity, expressed as a fraction of corrupted bits over transmission bits per second.
ESCON: IBM’s “Planning for Enterprise Systems Connection Links” provides information on fiber optic cable types & environment for ESCON capable devices. ESCON is intended for use in a mainframe environment rather than for local area networking or telecommunications.
ESDI: See Enhanced Small Device Interface
Establishment Procedure: The ASCII term for initial handshaking, a sequence in data transfer. During Establishment Procedure, the two communicating DTE's may exchange identities & confirm that they are able to transfer data.
ETB: See End of Transmission Block
Ethernet: A 10 Mbps network standard using CSMA/CD access. It was developed by Xerox, DEC & Intel. See also Fast Ethernet.
EtherTalk: AppleTalk protocol governing Ethernet transmissions. Also the Apple computer Ethernet adapter & drivers.
Ethertype: A 2 byte code indicating protocol type in an Ethernet packet. ETX: (End of Text) A control character in the DLG. ETX indicates the end of text information in a block.
Even Parity: A "dumb" terminal data-verification method in which each character must have an even number of "1" bits.
Expanded Memory: A PC's address memory (above 1 Meg).
EXT: End of Text
Extended Binary Coded Decimal Interchange Code: (EBCDIC) An 8 bit character code used primarily in IBM equipment; the code provides for 256 different bit patterns; compare with ASCII.
Extended Industry Standard Architecture: (EISA) A 32 bit adaptation of the 8 & 16 bit buses originally developed by IBM & now standard in almost all PC's that use Intel 8086, 80286 & 80386 microprocessors. The EISA bus is joint development of COMPAQ & other PC manufactures.
Extended Memory: A PC's address memory (640K to 1 Meg.)
Exterior Gateway Protocol: (EGP) A protocol used to advertise the OP address of one networks system to another. Each individual system must use EGP to advertise their reachability by the routing system.
External Storage Controller: A sub-unit in a computer or attached to a computer that manages the movement of data between the computer & the external storage device(s), such as, disk drives & tape units.

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